From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Wed, 21 Nov 2007 16:50:06 -0800 (PST) Received: from larry.melbourne.sgi.com (larry.melbourne.sgi.com [134.14.52.130]) by oss.sgi.com (8.12.11.20060308/8.12.10/SuSE Linux 0.7) with SMTP id lAM0nwGX016746 for ; Wed, 21 Nov 2007 16:50:01 -0800 Date: Thu, 22 Nov 2007 11:50:03 +1100 From: David Chinner Subject: [PATCH 2/2] Debug - don't exhaustively check the AIL on every operation Message-ID: <20071122005003.GQ114266761@sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: xfs-oss Cc: xfs-dev Checking the entire AIL on every insert and remove is prohibitively expensive - the sustained sequntial create rate on a single disk drops from about 1800/s to 60/s because of this checking resulting in the xfslogd becoming cpu bound. By default on debug builds, only check the next and previous entries in the list to ensure they are ordered correctly. If you really want, define XFS_TRANS_DEBUG to use the old behaviour. Signed-off-by: Dave Chinner --- fs/xfs/xfs_trans_ail.c | 37 ++++++++++++++++++++++++++++--------- 1 file changed, 28 insertions(+), 9 deletions(-) Index: 2.6.x-xfs-new/fs/xfs/xfs_trans_ail.c =================================================================== --- 2.6.x-xfs-new.orig/fs/xfs/xfs_trans_ail.c 2007-11-22 10:34:01.564358689 +1100 +++ 2.6.x-xfs-new/fs/xfs/xfs_trans_ail.c 2007-11-22 10:34:03.320134239 +1100 @@ -34,9 +34,9 @@ STATIC xfs_log_item_t * xfs_ail_min(xfs_ STATIC xfs_log_item_t * xfs_ail_next(xfs_ail_entry_t *, xfs_log_item_t *); #ifdef DEBUG -STATIC void xfs_ail_check(xfs_ail_entry_t *); +STATIC void xfs_ail_check(xfs_ail_entry_t *, xfs_log_item_t *); #else -#define xfs_ail_check(a) +#define xfs_ail_check(a,l) #endif /* DEBUG */ @@ -563,7 +563,7 @@ xfs_ail_insert( next_lip->li_ail.ail_forw = lip; lip->li_ail.ail_forw->li_ail.ail_back = lip; - xfs_ail_check(base); + xfs_ail_check(base, lip); return; } @@ -577,12 +577,12 @@ xfs_ail_delete( xfs_log_item_t *lip) /* ARGSUSED */ { + xfs_ail_check(base, lip); lip->li_ail.ail_forw->li_ail.ail_back = lip->li_ail.ail_back; lip->li_ail.ail_back->li_ail.ail_forw = lip->li_ail.ail_forw; lip->li_ail.ail_forw = NULL; lip->li_ail.ail_back = NULL; - xfs_ail_check(base); return lip; } @@ -626,13 +626,13 @@ xfs_ail_next( */ STATIC void xfs_ail_check( - xfs_ail_entry_t *base) + xfs_ail_entry_t *base, + xfs_log_item_t *lip) { - xfs_log_item_t *lip; xfs_log_item_t *prev_lip; - lip = base->ail_forw; - if (lip == (xfs_log_item_t*)base) { + prev_lip = base->ail_forw; + if (prev_lip == (xfs_log_item_t*)base) { /* * Make sure the pointers are correct when the list * is empty. @@ -642,9 +642,27 @@ xfs_ail_check( } /* + * Check the next and previous entries are valid. + */ + ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0); + prev_lip = lip->li_ail.ail_back; + if (prev_lip != (xfs_log_item_t*)base) { + ASSERT(prev_lip->li_ail.ail_forw == lip); + ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0); + } + prev_lip = lip->li_ail.ail_forw; + if (prev_lip != (xfs_log_item_t*)base) { + ASSERT(prev_lip->li_ail.ail_back == lip); + ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) >= 0); + } + + +#ifdef XFS_TRANS_DEBUG + /* * Walk the list checking forward and backward pointers, * lsn ordering, and that every entry has the XFS_LI_IN_AIL - * flag set. + * flag set. This is really expensive, so only do it when + * specifically debugging the transaction subsystem. */ prev_lip = (xfs_log_item_t*)base; while (lip != (xfs_log_item_t*)base) { @@ -659,5 +677,6 @@ xfs_ail_check( } ASSERT(lip == (xfs_log_item_t*)base); ASSERT(base->ail_back == prev_lip); +#endif /* XFS_TRANS_DEBUG */ } #endif /* DEBUG */